The objective of this proposal is to provide core support for the activities of the Johns Hopkins Center for Alternatives to Animal Testing (CAAT). The Center is a focus for the development of in vitro toxicity testing methodologies as well as a mechanism to communicate new developments to academia, government, industry and interested public organizations. The major activities of the Center are the Research Program, consisting of the Research Grants Program and the In Vitro Toxicology Laboratory, and the Communications/Education program. the Research Grants program supports international research aimed at developing the scientific basis for in vitro toxicity testing. The In Vitro Toxicology Laboratory, located at the Johns Hopkins School of Hygiene and Public Health, provides a unique resource for outside researchers from academia, government or industry to address research problems in in vitro toxicity testing. The Communications/Education Program provides mechanisms, including symposia, a newletter and a book series, to transfer the latest technological developments in alternative testing methodologies to the user audience. The ultimate goal of the Center is to foster the development of scientifically validated alternative methodologies which can be employed to provide the toxicological database for human risk assessment of chemical agents.